The tight-tuff heavy oil reservoir exhibits severe heterogeneity and is characterized by high density,high viscosity,and a high wax content,posing significant challenges for its development.While CO_(2)huffand-puff(H-...The tight-tuff heavy oil reservoir exhibits severe heterogeneity and is characterized by high density,high viscosity,and a high wax content,posing significant challenges for its development.While CO_(2)huffand-puff(H-n-P)enhances oil recovery,these reservoirs struggle with low displacement efficiency.This study proposes a method that combines CO_(2)with an oil-soluble viscosity reducer to improve displacement efficiency in the H-n-P process for tight-tuff heavy oil reservoirs.It also focuses on evaluating pore utilization limits and optimizing the injection strategy.Core samples and crude oil from the TH oilfield(a tight-tuff heavy oil reservoir)were used to conduct online NMR core flooding experiments,including depletion development,water,CO_(2),and HDC(CO_(2)combined with an oil-soluble viscosity reducer)H-n-P injection processes.A single-porosity model accurately reflecting its geological characteristics was developed using the GEM component simulator within the CMG numerical simulation software to investigate the optimized schemes and the enhanced oil recovery potential for a tight-tuff heavy oil reservoir in the TH oilfield.This model was utilized to evaluate the impact of various injection strategies on oilfield recovery efficiency.The study was designed and implemented with five distinct injection schemes.Results showed that oil was produced primarily from large and medium pores during the depletion stage,while water H-n-P,with CO_(2)H-n-P,first targeted macropores,then mesopores,and micropores.The lower pore utilization limit was 0.0267μm.In the HDC H-n-P process,most oil was recovered from water-flooded pores.Still,HDC's lower injection capacity increased the pore utilization limit to 0.03μm,making micropore recovery difficult.Experimental and modeling results suggest that the optimal develo p ment plan for the TH oilfield is one cycle of HDC H-n-P followed by two cycles of CO_(2)H-n-P.This strategy leverages HDC's ability to promote water and oil recovery in the early stage and mass transfer and extraction capacity of CO_(2)in later cycles.Additionally,the characteristics of CO_(2)and HDC H-n-P processes,pore utilization,and recoverable oil(at the pore scale)were evaluated.The results of this study are crucial for refining the reservoir development plan.展开更多
三塘湖盆地多口探井相继在条湖组沉凝灰岩储集层中获得工业油流,使其成为吐哈油田热点勘探领域。研究表明：沉凝灰岩的有机碳含量高、厚度大,是良好的烃源岩;储集层岩性除沉凝灰岩外,夹有生物碎屑、炭屑及少量泥质条带,具有一定的沉积特...三塘湖盆地多口探井相继在条湖组沉凝灰岩储集层中获得工业油流,使其成为吐哈油田热点勘探领域。研究表明：沉凝灰岩的有机碳含量高、厚度大,是良好的烃源岩;储集层岩性除沉凝灰岩外,夹有生物碎屑、炭屑及少量泥质条带,具有一定的沉积特征;储集层孔隙度为5.5%~24.0%,渗透率普遍小于0.5 m D,含油饱和度平均在70%以上,属于大孔隙、特低渗、高含油饱和度的沉凝灰岩致密油藏。通过Δlog R方法开展烃源岩测井定量评价;以岩石薄片鉴定和全岩矿物分析为基础,通过岩心刻度测井,建立和完善沉凝灰岩与泥岩等的识别方法和评价标准;结合岩心分析、CT扫描和毛管压力曲线资料开展储集层微观特征研究;利用组合式测井资料开展有效储集层物性评价和孔隙度计算,在岩性油藏整体认识的基础上开展含油性评价。基本形成了一套沉凝灰岩致密油藏测井评价配套技术与方法,在生产中取得了较好的应用效果。展开更多
基金funded by the Natural Science Foundation of Beijing Municipality(3232028)the National Natural Science Foundation of China(52274053)the National Foreign Expert Individual Project(H20240045)。
文摘The tight-tuff heavy oil reservoir exhibits severe heterogeneity and is characterized by high density,high viscosity,and a high wax content,posing significant challenges for its development.While CO_(2)huffand-puff(H-n-P)enhances oil recovery,these reservoirs struggle with low displacement efficiency.This study proposes a method that combines CO_(2)with an oil-soluble viscosity reducer to improve displacement efficiency in the H-n-P process for tight-tuff heavy oil reservoirs.It also focuses on evaluating pore utilization limits and optimizing the injection strategy.Core samples and crude oil from the TH oilfield(a tight-tuff heavy oil reservoir)were used to conduct online NMR core flooding experiments,including depletion development,water,CO_(2),and HDC(CO_(2)combined with an oil-soluble viscosity reducer)H-n-P injection processes.A single-porosity model accurately reflecting its geological characteristics was developed using the GEM component simulator within the CMG numerical simulation software to investigate the optimized schemes and the enhanced oil recovery potential for a tight-tuff heavy oil reservoir in the TH oilfield.This model was utilized to evaluate the impact of various injection strategies on oilfield recovery efficiency.The study was designed and implemented with five distinct injection schemes.Results showed that oil was produced primarily from large and medium pores during the depletion stage,while water H-n-P,with CO_(2)H-n-P,first targeted macropores,then mesopores,and micropores.The lower pore utilization limit was 0.0267μm.In the HDC H-n-P process,most oil was recovered from water-flooded pores.Still,HDC's lower injection capacity increased the pore utilization limit to 0.03μm,making micropore recovery difficult.Experimental and modeling results suggest that the optimal develo p ment plan for the TH oilfield is one cycle of HDC H-n-P followed by two cycles of CO_(2)H-n-P.This strategy leverages HDC's ability to promote water and oil recovery in the early stage and mass transfer and extraction capacity of CO_(2)in later cycles.Additionally,the characteristics of CO_(2)and HDC H-n-P processes,pore utilization,and recoverable oil(at the pore scale)were evaluated.The results of this study are crucial for refining the reservoir development plan.
文摘三塘湖盆地多口探井相继在条湖组沉凝灰岩储集层中获得工业油流,使其成为吐哈油田热点勘探领域。研究表明：沉凝灰岩的有机碳含量高、厚度大,是良好的烃源岩;储集层岩性除沉凝灰岩外,夹有生物碎屑、炭屑及少量泥质条带,具有一定的沉积特征;储集层孔隙度为5.5%~24.0%,渗透率普遍小于0.5 m D,含油饱和度平均在70%以上,属于大孔隙、特低渗、高含油饱和度的沉凝灰岩致密油藏。通过Δlog R方法开展烃源岩测井定量评价;以岩石薄片鉴定和全岩矿物分析为基础,通过岩心刻度测井,建立和完善沉凝灰岩与泥岩等的识别方法和评价标准;结合岩心分析、CT扫描和毛管压力曲线资料开展储集层微观特征研究;利用组合式测井资料开展有效储集层物性评价和孔隙度计算,在岩性油藏整体认识的基础上开展含油性评价。基本形成了一套沉凝灰岩致密油藏测井评价配套技术与方法,在生产中取得了较好的应用效果。
